Shock & Sepsis

Definition:

Shock is a state of circulatory dysfunction in which tissue O₂ delivery is less than required. If untreated, multi-organ failure and death result. Shock is the final common pathway of numerous disease states.

Aetiology:

Can be broadly classified into the following categories:

• Hypovolaemic
  
• Cardiogenic
  
• Septic
  
• Endocrine
  
• Anaphylactic

Clinical signs:

Clinical signs are for the most part non-specific, and include tachycardia, hypotension - particularly decreased diastolic BP, gallop rhythm, oliguria, and altered consciuosness. Additional signs of specific underlying disorder should be sought.

Management:

Management is generally supportive. Specific treatment for the underlying disorder is unlikely to be effective in the short term with the exception of adrenaline in anaphylaxis or hydrocortisone in Addisonian crisis. As specific therapy will lead to dramatic improvement in these patients, it is critical to consider both conditions early in the resuscitation and treat appropriately.

Anaphylaxis

Anaphylaxis is differentiated by a possible history of exposure to triggering event (ingestion of nuts or seafood, bee sting, etc), together with clinical features of stridor and wheeze, often with swelling of the mouth and tongue or around a bite site. Hereditary angio-neurotic oedema (HANE) is a special case of anaphylactic shock where an enzyme deficiency (C_1q esterase) - which may be dominantly inherited or arise as a spontaneous mutation - results in uncontrolled complement pathway activation presenting clinically as anaphylaxis without an identifiable trigger. Adrenaline should be titrated against symptoms in 10 ug/kg doses (=0.1 ml/kg of 1:10,000) IV. FFP may be useful for patients with HANE as it contains C_1q esterase.

Addisonian crisis

Addisonian crisis should be suspected in patients abruptly withdrawn from chronic steroid therapy, but is more likely to present de novo in early infancy from variants of congenital adrenal hyperplasia (CAH), congenital adrenal hypoplasia, or rarely adrenoleucodystrophy - clues to CAH are ambiguous genitalia or hyperpigmentation of male genitalia; electrolyte disturbances of hyponatraemia and hyperkalaemia are also common, as is hypoglycaemia. Patients with known glucocorticoid deficiencies on replacement therapy may also present if steroid doses are not increased appropriately during intercurrent infections or other stressful events. Rarely, addisonian crisis may complicate meningococcal sepsis (Waterhouse-Friderichson Sydrome, with bilateral adrenal haemorrhagic infarction), and hydrocortisone should be considered in patients with meningococcal disease and refractory hypotension. Hydrocortisone doses are 50 mg IV for infants - toddlers, and 100 - 150 mg IV for older children - adults.

Management for all Shocked Patients

Otherwise, management is similar for all shocked patients:

• Establish parenteral access, preferably with 2 IV lines. If IV access cannot be established, an intra-osseous cannula should be placed.
  
• Provide supplemental O₂
  .
• If cardiogenic shock (eg myocarditis, ventricular arrhythmias etc) is excluded, give colloid in 10 ml/kg boluses until BP and HR return to acceptable levels. Cardiogenic shock - suggested by cardiomegally, peripheral and pulmonary oedema, low voltages on ECG, AV valvar regurgitation murmers - should be treated primarily with inotropes, with volume resuscitation used cautiously if at all.
  

Further supportive treatment may include intubation and inotropic support :

• Intubation should be considered for any patient with depressed consciousness (GCS <= 8) secondary to shock.
  
• Inotropic support should be considered for any patient unresponsive to colloid challenge of 40 - 50 ml/kg in total. Inotrope selection will depend to some extent on aetiology, but dopamine at a starting dose of 5 - 10 ug/kg/min is a reasonable first choice in most situations (15 mg/kg in 50 ml D5 or NS at 1 - 2 ml/hour).
  
• Antibiotics should be given in all cases of suspected septic shock, however fundamentals such as airway control and circulatory support must be addressed as a higher priority. Ceftriaxone 100 mg/kg IV or IM provides good broad spectrum coverage in most situations. Special cases such as neonates and immunosuppressed patients will require alternative or additional drugs (see unwell infants and febrile neutropaenia protocols).